To fully use high-pressure air, the two-stage piston expander (TSPE) has been widely studied. The... more To fully use high-pressure air, the two-stage piston expander (TSPE) has been widely studied. The following factors obstruct the use of the TSPE: A high expansion ratio will inevitably result in a lower air temperature in the cylinder, causing adverse effects such as ice blockage and lubricating oil freezing; the residual air from the I-stage cylinder will all flow into the II-stage cylinder, causing a large reverse force to the I-stage piston during the working process. To address the above problems, a modified two-stage piston expander (M-TSPE) based on spray heat transfer is proposed. Firstly, the working principle of the M-TSPE is introduced, followed by the construction of a mathematical model of the M-TSPE. Secondly, the valve-timing of the M-TSPE is determined and compared with the output power and efficiency of the TSPE. The output power and efficiency of the M-TSPE are increased by 57.58% and 13.28%, respectively. Then, the performance parameters of the M-TSPE with and with...
The random nature of wind energy is an important reason for the low energy utilization rate of wi... more The random nature of wind energy is an important reason for the low energy utilization rate of wind farms. The use of a compressed air energy storage system (CAES) can help reduce the random characteristics of wind power generation while also increasing the utilization rate of wind energy. However, the unreasonable capacity allocation of the CAES system results in high capital investment and a long payback period. In order to improve the economic benefits of energy storage, this paper studies the capacity configuration of compressed air energy storage systems under the condition of wind energy uncertainty. First, the typical hourly power distribution of wind power generation was obtained using historical data. Factors such as user load demand, time-of-use price of the power grid, system investment cost, power shortage cost, and power sales revenue were considered. Then, a model was built with the charging and discharging power and gas storage capacity of the CAES system as constrain...
Proceedings of the Institution of Civil Engineers - Energy, 2022
Dual-water tank energy storage has been adopted in some solar heating systems to mitigate solar e... more Dual-water tank energy storage has been adopted in some solar heating systems to mitigate solar energy randomness and instability. Two types of dual-water tank solar heating (DWTSH) system are introduced and analysed in this paper, one is the traditional DWTSH system and the other has a thermal buffer and is named TB-DWTSH. Analysis software called TRNSYS was used for the simulation, the tank water temperatures and solar guarantee of two systems were measured and compared. A new thermal comfort evaluation criterion for the solar heating system is briefly introduced. The TRNSYS model was verified by a pilot project of a traditional DWTSH system. The heating systems were assessed based on the solar guarantee rate of the heating system and the thermal comfort index. The outcome showed that the simulation results are generally consistent with the experimental results. Compared with the traditional DWTSH system, the comfort index could be greatly improved in the TB-DWTSH system between 8...
Abstract Compared with other types of energy storage systems, compressed air energy storage (CAES... more Abstract Compared with other types of energy storage systems, compressed air energy storage (CAES) system has the advantages of low cost, long life, and less impact on environmental. Low cycle efficiency limits its development. Enhancement of the heat transfer between air and environment to achieve isothermal compression is an effective method to improve the round trip efficiency of CAES systems. The spray heat exchange method is proposed to achieve isothermal compression. In order to obtain an accurate heat transfer process model, this paper takes into account that the process of water mist spreading from the nozzle to the whole cylinder will lead to local air and water mist heat transfer in the cylinder, and then divides the area in the cylinder into two parts to analyze and calculate the gas state. To verify the rationality of the diffusion model, a high-speed camera is used to observe the spray diffusion process. Meanwhile, the accuracy of the isothermal CAES system model is verified by literature experimental data, and finally the influence of water spray system parameters is obtained. The research results show that to gain fast heat transfer rate, a spray angle is equal to 60°; when the nozzle diameter is reduced from 0.6 mm to 0.4 mm, the compression efficiency of the system increases from 85.53 % to 89.25 %; The orthogonal design method is used to obtain the maximum total efficiency of the system under the given conditions, when the nozzle diameter is 0.6 mm and the water pressure is 0.2 MPa, and its value reaches 88 %. This research provides theoretical support for the in-cylinder spray isothermal CAES system.
Abstract Regulation of surface wettability is of vital significance to diamond-like carbon (DLC) ... more Abstract Regulation of surface wettability is of vital significance to diamond-like carbon (DLC) serving as multi-functional coatings in many important fields. In this study, hydrogen-free DLC films with highly adjustable surface wettability induced by surface local hybridized structures were deposited on silicon substrates by RF magnetron sputtering under different substrate temperatures and RF powers. A non-monotonic dependency of surface wettability on the hybridization states, which is just inverse for polar and non-polar liquids, was found on the homogeneous DLC films with nanoscale surface roughness. In particular, the wetting transition from hydrophilicity to hydrophobicity occurred on the DLC films in contact with water. A clear picture about the essential correlation of surface wettability to microstructures of DLC films was drawn in terms of detailed analysis of surface energy components associated with the evolution of sp2-C bonds or clusters in content, type and distortion. Further, a possible mechanism accounting for the wetting transition of the DLC films was also proposed. This work aims to reveal the wetting nature of hydrogen-free DLC films versus graphite and diamond, and provide an available strategy to fabricate high-performance DLC films with special surface wettability used in aqueous environment.
Pneumatic actuating systems are an important power system in industrial applications. Due to exha... more Pneumatic actuating systems are an important power system in industrial applications. Due to exhaust loss, however, pneumatic actuating systems have suffered from a low utilization of compressed air. To recycle the exhaust energy, a novel pneumatic circuit was proposed to realize energy savings through recycling exhaust energy. The circuit consisted of three two-position three-way switch valves, which were used to control the exhaust flows into a gas tank or the ambient environment. This paper introduced the energy recovery configuration and working principles and built a mathematical model of its working process. Then, the mathematical model was verified by experiments. Finally, through experiments in which the air supply pressure, the critical pressure and the volume of the gas tank were regulated, the energy recovery characteristics of the pneumatic actuating system were obtained. Using the new circuit, the experimental results showed that the energy recovery efficiency exceeded ...
Cough is a respiratory protective behavior for clearing the secretion. The cough process can be c... more Cough is a respiratory protective behavior for clearing the secretion. The cough process can be characterized by three features which are cough peak flow rate, peak velocity time, and cough expired volume. The cough expired volume (CEV) and the cough peak flow rate (CPFR) are important for medical diagnosis and cough effectiveness assessment. In this study, the CEV and CPFR values of 700 healthy participants were measured and collected by using a portable pulmonary function device. The gender, age, height, weight, and smoking status information of the 700 participants were also collected. Meanwhile, the integration of backpropagation neural network and genetic algorithm (GA-BP) method was developed to estimate CEV and CPFR values. The results showed that the estimation accuracy of GA-BP method exceeds 90%, which indicates that the GA-BP method could be effectively used for CEV and CPFR value estimation. Furthermore, the method proposed in this paper could be useful for medical diagn...
Due to the high variability of weather-dependent renewable energy resources, electrical energy st... more Due to the high variability of weather-dependent renewable energy resources, electrical energy storage systems have received much attention. In this field, one of the most promising technologies is compressed-air energy storage (CAES). In this article, the concept and classification of CAES are reviewed, and the cycle efficiency and effective energy are analyzed in detail to enhance the current understanding of CAES. Furthermore, the importance of the real-gas properties of air is discussed. Related research on adiabatic CAES and isothermal CAES is also presented.
Recently, the cruising duration is a vital parameter of fuel-powered unmanned aerial vehicles (UA... more Recently, the cruising duration is a vital parameter of fuel-powered unmanned aerial vehicles (UAVs), and it is directly determined by the power characteristics of the aircraft engine in the UAV. In this study, to prolong the flight duration and enhance the power and efficiency of a UAV, an aircraft engine is analyzed based on the fuel injection control system and output power characteristics. First, the mathematical model of a fuel-controlled engine is constructed. In addition, the experimental stations of the aircraft engine are set up to verify the mathematical model. Furthermore, the effects of key parameters on the engine power characteristics are examined. By the experimental and simulation studies validity of the mathematical model is effectively verified which indicates that the increased rotating speed decreases the power efficiency of the aircraft engine, and reducing the fuel injection pulse width from 5 ms to 3.5 ms increases the power efficiency by 10%. Moreover, increasing the advance angle of ignition from 10 • to 40 • improves the power efficiency by 5%. In addition, when the fuel injection delay width increases from 0.5 mm to 1.5 mm at an engine speed between 3500 rpm and 4000 rpm, the power efficiency is improved by 6%. Finally, when the engine speed is higher than 4000 rpm, increasing the propeller rotor diameter from 650 mm to 800 mm enhances the power efficiency of the aircraft engine by approximately 5%. This research can be considered as the fuel injection system optimization and cruising duration improvement of a fuel-powered UAV. INDEX TERMS Aircraft engine, fuel injection control system, power characteristics, efficiency, fuel-powered unmanned aerial vehicle. I. INTRODUCTION Recently, fuel-powered unmanned air vehicles (UAVs) have been widely applied in agriculture, plant protection, transportation, and field surveillance due to their simple structure, easy control, steady running, and landform independence [1]-[5]. The cruising duration has gradually become a key technical indicator to evaluate the UAV performance since a short cruising duration will limit the UAV application for long-distance flights. Presently, the cruising duration of a typical small UAV is less than 1 h [6], [7], which cannot satisfy the requirements of long-duration missions. The associate editor coordinating the review of this manuscript and approving it for publication was Tao Wang.
Accurate fuel injection control of aircraft engine can optimize the energy efficiency of UAV powe... more Accurate fuel injection control of aircraft engine can optimize the energy efficiency of UAV power system while meeting the propeller speed requirement. Traditional injection control method such as open-loop calibration causes instability of fuel supply which brings the risk of power loss of UAV. Considering that the closed-loop control of AFR can ensure a stable fuel feeding, this paper proposes an AFR control based fuel supply strategy in order to improve the efficiency of fuel-powered UAV while obtaining the required engine speed. According to the optimum fuel injection results, we implement fuzzy-PID method to control the set AFR in different situations. Through simulation and experiment studies, the results indicate that, to begin with, the calibrated mathematical model of the aircraft engine is effective. Next, this fuel supply strategy based on AFR control can normally realize the engine speed regulation, and the applied control algorithm can eliminate the overshoot of AFR throughout all the working progress. What is more, the fuel supply strategy can averagely shorten the response time of the engine speed by about two seconds. In addition, compared with the open-loop calibration, in this work the power efficiency is improved by 9% to 33%. Last but not the least, the endurance can be improved by 30 min with a normal engine speed. This paper can be a reference for the optimization of UAV aircraft engine.
Traditional control method of air-fuel ratio (AFR) of aero engine can't meet the performance requ... more Traditional control method of air-fuel ratio (AFR) of aero engine can't meet the performance requirement of fuel-powered unmanned aerial vehicle (UAV), which may lead to efficiency reduction and emission increase. In order to improve the control accuracy, this paper proposes a new AFR control method based on fuzzy-PID. We analyze the control results under different working conditions by using adaptive fuzzy-PID. Through simulation and experimental studies, we can draw the conclusions as follows: compared with PID control method, firstly, AFR control error can be reduced by 80% in normal condition; secondly, the control error is reduced by 55% in rapid acceleration condition; in addition, the control error can be reduced by 71% in continuous disturbance condition; comparison results with existing Fuzzy-PID also show that the improved controller has advantage in terms of resisting rapid and continuous interferences; moreover, in practical application of fuzzy-PID control, the highest AFR errors are about 3%. In normal condition, the error is reduced from 5% to 1% compared with PID control, which demonstrates the effectiveness of the improved fuzzy-PID control model. This research can be a reference in the application of UAV aero engine control.
The open and close duration, angle, and pressure of the intake and exhaust valves substantially i... more The open and close duration, angle, and pressure of the intake and exhaust valves substantially influence compressed air engine efficiency and output power. In the actual prototype, the air distribution system can be of two types, cam air distribution type and rotary air distribution type. Compressed air engine based on the two types has been investigated. However, there have been debates over the advantages and disadvantages of these two technologies. The article aims to compare two technologies from the output power and energy efficiency. To verify theoretical analyses’ model, an experimental system is built to test the output power and efficiency of compressed air engine with cam air distribution system. It is shown that the output power of the compressed air engine with rotary air distribution system is higher than that of the compressed air engine with cam air distribution system. When the rotation speed is equal to 800 r/min, the output power of the compressed air engine with ...
2016 IEEE International Conference on Aircraft Utility Systems (AUS), 2016
With the development of general aviation, UAVs are increasingly used in all areas of our life. Ho... more With the development of general aviation, UAVs are increasingly used in all areas of our life. However, electric multi-rotor UAV can't achieve long-endurance, large load transport due to battery energy density. And hybrid power system is a perfect solution to this problem. This paper raised a parameter matching method of the UAV's hybrid power system related to the pulling force, required power and flight performance. The UAV's power demand was taken as an entry point for parameter matching, and the match result was based to select power components. The test results of the components performance proved the matching methods' feasibility and accuracy. The structure of hybrid coaxial rotors and multi-rotor UAV is also tested to be achievable.
To improve the condition of air and eliminate exhaust gas pollution, this article proposes a comp... more To improve the condition of air and eliminate exhaust gas pollution, this article proposes a compressed air power system. Instead of an internal combustion engine, the automobile is equipped with a compressed air engine, which transforms the energy of compressed air into mechanical motion energy. A prototype was built, and the compressed air engine was tested on an experimental platform. The output torque and energy efficiency were obtained from experimental results. When the supply pressure was set at 2 MPa and the speed was 420 r min−1, the output torque, the output power, and the energy efficiency were 56 N m, 1.93 kW, and 25%, respectively. To improve the efficiency of the system, a fuzzy logic speed control strategy is proposed and simulated. The experimental study verified that the theoretical evaluation of the system was reasonable, and this research can be referred to as the design and control of air-powered vehicles.
2013 International Conference on Materials for Renewable Energy and Environment, 2013
Future sustainable energy systems call for the introduction of integrated storage technologies. O... more Future sustainable energy systems call for the introduction of integrated storage technologies. One of these technologies is compressed air energy storage (CAES). In this paper, the principle of CAES is introduced, then the mathematical model about the process of CAES is analyzed. The parameter change in the engine cylinder is studied in the different crankshaft speed. The result is that the mechanism can produce efficient energy transfer with relative low crankshaft speed. This result is very important to design mechanism for compressed air energy storage.
To eliminate the pollutants exhausting, this paper presents an idea of using compressed air as th... more To eliminate the pollutants exhausting, this paper presents an idea of using compressed air as the power source for engines. Instead of an internal combustion (IC) engine, this automobile is equipped with a compressed air engines (CAEs), which transforms the energy of the compressed air into mechanical kinematic energy. Through analysis of the working process of a CAE, the mathematical model is setup. Experiments are carried out to verify the engine performance and the basic model’s validity. By selecting the appropriate reference values, the mathematical model is transformed to a dimensionless expression. The dimensionless speed and efficiency characteristics of the CAE are obtained. Through analysis, it can be obtained that the dimensionless average rotating speed is mainly determined by the intake duration angle, the dimensionless inertia parameter, the dimensionless exhaust pressure, and the scale factor of exhaust valve. Moreover, the efficiency of the CAE is mainly determined ...
The current research of compressed air engine (CAE) mainly focused on simulations and system inte... more The current research of compressed air engine (CAE) mainly focused on simulations and system integrations. However, energy efficiency and output torque of the CAE is limited, which restricts its application and popularization. In this paper, the working principles of CAE are briefly introduced. To set a foundation for the study on the optimization of the CAE, the basic mathematical model of working processes is set up. A pressure-compensated valve which can reduce the inertia force of the valve is proposed. To verify the mathematical model, the prototype with the newly designed pressure-compensated intake valve is built and the experiment is carried out, simulation and experimental results of the CAE are conducted, and pressures inside the cylinder and output torque of the CAE are obtained. Orthogonal design and grey relation analysis are utilized to optimize structural parameters. The experimental and optimized results show that, first of all, pressure inside the cylinder has the same changing tendency in both simulation curve and experimental curve. Secondly, the highest average output torque is obtained at the highest intake pressure and the lowest rotate speed. Thirdly, the optimization of the single-cylinder CAE can improve the working efficiency from an original 21.95% to 50.1%, an overall increase of 28.15%, and the average output torque increases also increases from 22.047 5 N • m to 22.439 N • m. This research designs a single-cylinder CAE with pressure-compensated intake valve, and proposes a structural parameters design method which improves the single-cylinder CAE performance.
To fully use high-pressure air, the two-stage piston expander (TSPE) has been widely studied. The... more To fully use high-pressure air, the two-stage piston expander (TSPE) has been widely studied. The following factors obstruct the use of the TSPE: A high expansion ratio will inevitably result in a lower air temperature in the cylinder, causing adverse effects such as ice blockage and lubricating oil freezing; the residual air from the I-stage cylinder will all flow into the II-stage cylinder, causing a large reverse force to the I-stage piston during the working process. To address the above problems, a modified two-stage piston expander (M-TSPE) based on spray heat transfer is proposed. Firstly, the working principle of the M-TSPE is introduced, followed by the construction of a mathematical model of the M-TSPE. Secondly, the valve-timing of the M-TSPE is determined and compared with the output power and efficiency of the TSPE. The output power and efficiency of the M-TSPE are increased by 57.58% and 13.28%, respectively. Then, the performance parameters of the M-TSPE with and with...
The random nature of wind energy is an important reason for the low energy utilization rate of wi... more The random nature of wind energy is an important reason for the low energy utilization rate of wind farms. The use of a compressed air energy storage system (CAES) can help reduce the random characteristics of wind power generation while also increasing the utilization rate of wind energy. However, the unreasonable capacity allocation of the CAES system results in high capital investment and a long payback period. In order to improve the economic benefits of energy storage, this paper studies the capacity configuration of compressed air energy storage systems under the condition of wind energy uncertainty. First, the typical hourly power distribution of wind power generation was obtained using historical data. Factors such as user load demand, time-of-use price of the power grid, system investment cost, power shortage cost, and power sales revenue were considered. Then, a model was built with the charging and discharging power and gas storage capacity of the CAES system as constrain...
Proceedings of the Institution of Civil Engineers - Energy, 2022
Dual-water tank energy storage has been adopted in some solar heating systems to mitigate solar e... more Dual-water tank energy storage has been adopted in some solar heating systems to mitigate solar energy randomness and instability. Two types of dual-water tank solar heating (DWTSH) system are introduced and analysed in this paper, one is the traditional DWTSH system and the other has a thermal buffer and is named TB-DWTSH. Analysis software called TRNSYS was used for the simulation, the tank water temperatures and solar guarantee of two systems were measured and compared. A new thermal comfort evaluation criterion for the solar heating system is briefly introduced. The TRNSYS model was verified by a pilot project of a traditional DWTSH system. The heating systems were assessed based on the solar guarantee rate of the heating system and the thermal comfort index. The outcome showed that the simulation results are generally consistent with the experimental results. Compared with the traditional DWTSH system, the comfort index could be greatly improved in the TB-DWTSH system between 8...
Abstract Compared with other types of energy storage systems, compressed air energy storage (CAES... more Abstract Compared with other types of energy storage systems, compressed air energy storage (CAES) system has the advantages of low cost, long life, and less impact on environmental. Low cycle efficiency limits its development. Enhancement of the heat transfer between air and environment to achieve isothermal compression is an effective method to improve the round trip efficiency of CAES systems. The spray heat exchange method is proposed to achieve isothermal compression. In order to obtain an accurate heat transfer process model, this paper takes into account that the process of water mist spreading from the nozzle to the whole cylinder will lead to local air and water mist heat transfer in the cylinder, and then divides the area in the cylinder into two parts to analyze and calculate the gas state. To verify the rationality of the diffusion model, a high-speed camera is used to observe the spray diffusion process. Meanwhile, the accuracy of the isothermal CAES system model is verified by literature experimental data, and finally the influence of water spray system parameters is obtained. The research results show that to gain fast heat transfer rate, a spray angle is equal to 60°; when the nozzle diameter is reduced from 0.6 mm to 0.4 mm, the compression efficiency of the system increases from 85.53 % to 89.25 %; The orthogonal design method is used to obtain the maximum total efficiency of the system under the given conditions, when the nozzle diameter is 0.6 mm and the water pressure is 0.2 MPa, and its value reaches 88 %. This research provides theoretical support for the in-cylinder spray isothermal CAES system.
Abstract Regulation of surface wettability is of vital significance to diamond-like carbon (DLC) ... more Abstract Regulation of surface wettability is of vital significance to diamond-like carbon (DLC) serving as multi-functional coatings in many important fields. In this study, hydrogen-free DLC films with highly adjustable surface wettability induced by surface local hybridized structures were deposited on silicon substrates by RF magnetron sputtering under different substrate temperatures and RF powers. A non-monotonic dependency of surface wettability on the hybridization states, which is just inverse for polar and non-polar liquids, was found on the homogeneous DLC films with nanoscale surface roughness. In particular, the wetting transition from hydrophilicity to hydrophobicity occurred on the DLC films in contact with water. A clear picture about the essential correlation of surface wettability to microstructures of DLC films was drawn in terms of detailed analysis of surface energy components associated with the evolution of sp2-C bonds or clusters in content, type and distortion. Further, a possible mechanism accounting for the wetting transition of the DLC films was also proposed. This work aims to reveal the wetting nature of hydrogen-free DLC films versus graphite and diamond, and provide an available strategy to fabricate high-performance DLC films with special surface wettability used in aqueous environment.
Pneumatic actuating systems are an important power system in industrial applications. Due to exha... more Pneumatic actuating systems are an important power system in industrial applications. Due to exhaust loss, however, pneumatic actuating systems have suffered from a low utilization of compressed air. To recycle the exhaust energy, a novel pneumatic circuit was proposed to realize energy savings through recycling exhaust energy. The circuit consisted of three two-position three-way switch valves, which were used to control the exhaust flows into a gas tank or the ambient environment. This paper introduced the energy recovery configuration and working principles and built a mathematical model of its working process. Then, the mathematical model was verified by experiments. Finally, through experiments in which the air supply pressure, the critical pressure and the volume of the gas tank were regulated, the energy recovery characteristics of the pneumatic actuating system were obtained. Using the new circuit, the experimental results showed that the energy recovery efficiency exceeded ...
Cough is a respiratory protective behavior for clearing the secretion. The cough process can be c... more Cough is a respiratory protective behavior for clearing the secretion. The cough process can be characterized by three features which are cough peak flow rate, peak velocity time, and cough expired volume. The cough expired volume (CEV) and the cough peak flow rate (CPFR) are important for medical diagnosis and cough effectiveness assessment. In this study, the CEV and CPFR values of 700 healthy participants were measured and collected by using a portable pulmonary function device. The gender, age, height, weight, and smoking status information of the 700 participants were also collected. Meanwhile, the integration of backpropagation neural network and genetic algorithm (GA-BP) method was developed to estimate CEV and CPFR values. The results showed that the estimation accuracy of GA-BP method exceeds 90%, which indicates that the GA-BP method could be effectively used for CEV and CPFR value estimation. Furthermore, the method proposed in this paper could be useful for medical diagn...
Due to the high variability of weather-dependent renewable energy resources, electrical energy st... more Due to the high variability of weather-dependent renewable energy resources, electrical energy storage systems have received much attention. In this field, one of the most promising technologies is compressed-air energy storage (CAES). In this article, the concept and classification of CAES are reviewed, and the cycle efficiency and effective energy are analyzed in detail to enhance the current understanding of CAES. Furthermore, the importance of the real-gas properties of air is discussed. Related research on adiabatic CAES and isothermal CAES is also presented.
Recently, the cruising duration is a vital parameter of fuel-powered unmanned aerial vehicles (UA... more Recently, the cruising duration is a vital parameter of fuel-powered unmanned aerial vehicles (UAVs), and it is directly determined by the power characteristics of the aircraft engine in the UAV. In this study, to prolong the flight duration and enhance the power and efficiency of a UAV, an aircraft engine is analyzed based on the fuel injection control system and output power characteristics. First, the mathematical model of a fuel-controlled engine is constructed. In addition, the experimental stations of the aircraft engine are set up to verify the mathematical model. Furthermore, the effects of key parameters on the engine power characteristics are examined. By the experimental and simulation studies validity of the mathematical model is effectively verified which indicates that the increased rotating speed decreases the power efficiency of the aircraft engine, and reducing the fuel injection pulse width from 5 ms to 3.5 ms increases the power efficiency by 10%. Moreover, increasing the advance angle of ignition from 10 • to 40 • improves the power efficiency by 5%. In addition, when the fuel injection delay width increases from 0.5 mm to 1.5 mm at an engine speed between 3500 rpm and 4000 rpm, the power efficiency is improved by 6%. Finally, when the engine speed is higher than 4000 rpm, increasing the propeller rotor diameter from 650 mm to 800 mm enhances the power efficiency of the aircraft engine by approximately 5%. This research can be considered as the fuel injection system optimization and cruising duration improvement of a fuel-powered UAV. INDEX TERMS Aircraft engine, fuel injection control system, power characteristics, efficiency, fuel-powered unmanned aerial vehicle. I. INTRODUCTION Recently, fuel-powered unmanned air vehicles (UAVs) have been widely applied in agriculture, plant protection, transportation, and field surveillance due to their simple structure, easy control, steady running, and landform independence [1]-[5]. The cruising duration has gradually become a key technical indicator to evaluate the UAV performance since a short cruising duration will limit the UAV application for long-distance flights. Presently, the cruising duration of a typical small UAV is less than 1 h [6], [7], which cannot satisfy the requirements of long-duration missions. The associate editor coordinating the review of this manuscript and approving it for publication was Tao Wang.
Accurate fuel injection control of aircraft engine can optimize the energy efficiency of UAV powe... more Accurate fuel injection control of aircraft engine can optimize the energy efficiency of UAV power system while meeting the propeller speed requirement. Traditional injection control method such as open-loop calibration causes instability of fuel supply which brings the risk of power loss of UAV. Considering that the closed-loop control of AFR can ensure a stable fuel feeding, this paper proposes an AFR control based fuel supply strategy in order to improve the efficiency of fuel-powered UAV while obtaining the required engine speed. According to the optimum fuel injection results, we implement fuzzy-PID method to control the set AFR in different situations. Through simulation and experiment studies, the results indicate that, to begin with, the calibrated mathematical model of the aircraft engine is effective. Next, this fuel supply strategy based on AFR control can normally realize the engine speed regulation, and the applied control algorithm can eliminate the overshoot of AFR throughout all the working progress. What is more, the fuel supply strategy can averagely shorten the response time of the engine speed by about two seconds. In addition, compared with the open-loop calibration, in this work the power efficiency is improved by 9% to 33%. Last but not the least, the endurance can be improved by 30 min with a normal engine speed. This paper can be a reference for the optimization of UAV aircraft engine.
Traditional control method of air-fuel ratio (AFR) of aero engine can't meet the performance requ... more Traditional control method of air-fuel ratio (AFR) of aero engine can't meet the performance requirement of fuel-powered unmanned aerial vehicle (UAV), which may lead to efficiency reduction and emission increase. In order to improve the control accuracy, this paper proposes a new AFR control method based on fuzzy-PID. We analyze the control results under different working conditions by using adaptive fuzzy-PID. Through simulation and experimental studies, we can draw the conclusions as follows: compared with PID control method, firstly, AFR control error can be reduced by 80% in normal condition; secondly, the control error is reduced by 55% in rapid acceleration condition; in addition, the control error can be reduced by 71% in continuous disturbance condition; comparison results with existing Fuzzy-PID also show that the improved controller has advantage in terms of resisting rapid and continuous interferences; moreover, in practical application of fuzzy-PID control, the highest AFR errors are about 3%. In normal condition, the error is reduced from 5% to 1% compared with PID control, which demonstrates the effectiveness of the improved fuzzy-PID control model. This research can be a reference in the application of UAV aero engine control.
The open and close duration, angle, and pressure of the intake and exhaust valves substantially i... more The open and close duration, angle, and pressure of the intake and exhaust valves substantially influence compressed air engine efficiency and output power. In the actual prototype, the air distribution system can be of two types, cam air distribution type and rotary air distribution type. Compressed air engine based on the two types has been investigated. However, there have been debates over the advantages and disadvantages of these two technologies. The article aims to compare two technologies from the output power and energy efficiency. To verify theoretical analyses’ model, an experimental system is built to test the output power and efficiency of compressed air engine with cam air distribution system. It is shown that the output power of the compressed air engine with rotary air distribution system is higher than that of the compressed air engine with cam air distribution system. When the rotation speed is equal to 800 r/min, the output power of the compressed air engine with ...
2016 IEEE International Conference on Aircraft Utility Systems (AUS), 2016
With the development of general aviation, UAVs are increasingly used in all areas of our life. Ho... more With the development of general aviation, UAVs are increasingly used in all areas of our life. However, electric multi-rotor UAV can't achieve long-endurance, large load transport due to battery energy density. And hybrid power system is a perfect solution to this problem. This paper raised a parameter matching method of the UAV's hybrid power system related to the pulling force, required power and flight performance. The UAV's power demand was taken as an entry point for parameter matching, and the match result was based to select power components. The test results of the components performance proved the matching methods' feasibility and accuracy. The structure of hybrid coaxial rotors and multi-rotor UAV is also tested to be achievable.
To improve the condition of air and eliminate exhaust gas pollution, this article proposes a comp... more To improve the condition of air and eliminate exhaust gas pollution, this article proposes a compressed air power system. Instead of an internal combustion engine, the automobile is equipped with a compressed air engine, which transforms the energy of compressed air into mechanical motion energy. A prototype was built, and the compressed air engine was tested on an experimental platform. The output torque and energy efficiency were obtained from experimental results. When the supply pressure was set at 2 MPa and the speed was 420 r min−1, the output torque, the output power, and the energy efficiency were 56 N m, 1.93 kW, and 25%, respectively. To improve the efficiency of the system, a fuzzy logic speed control strategy is proposed and simulated. The experimental study verified that the theoretical evaluation of the system was reasonable, and this research can be referred to as the design and control of air-powered vehicles.
2013 International Conference on Materials for Renewable Energy and Environment, 2013
Future sustainable energy systems call for the introduction of integrated storage technologies. O... more Future sustainable energy systems call for the introduction of integrated storage technologies. One of these technologies is compressed air energy storage (CAES). In this paper, the principle of CAES is introduced, then the mathematical model about the process of CAES is analyzed. The parameter change in the engine cylinder is studied in the different crankshaft speed. The result is that the mechanism can produce efficient energy transfer with relative low crankshaft speed. This result is very important to design mechanism for compressed air energy storage.
To eliminate the pollutants exhausting, this paper presents an idea of using compressed air as th... more To eliminate the pollutants exhausting, this paper presents an idea of using compressed air as the power source for engines. Instead of an internal combustion (IC) engine, this automobile is equipped with a compressed air engines (CAEs), which transforms the energy of the compressed air into mechanical kinematic energy. Through analysis of the working process of a CAE, the mathematical model is setup. Experiments are carried out to verify the engine performance and the basic model’s validity. By selecting the appropriate reference values, the mathematical model is transformed to a dimensionless expression. The dimensionless speed and efficiency characteristics of the CAE are obtained. Through analysis, it can be obtained that the dimensionless average rotating speed is mainly determined by the intake duration angle, the dimensionless inertia parameter, the dimensionless exhaust pressure, and the scale factor of exhaust valve. Moreover, the efficiency of the CAE is mainly determined ...
The current research of compressed air engine (CAE) mainly focused on simulations and system inte... more The current research of compressed air engine (CAE) mainly focused on simulations and system integrations. However, energy efficiency and output torque of the CAE is limited, which restricts its application and popularization. In this paper, the working principles of CAE are briefly introduced. To set a foundation for the study on the optimization of the CAE, the basic mathematical model of working processes is set up. A pressure-compensated valve which can reduce the inertia force of the valve is proposed. To verify the mathematical model, the prototype with the newly designed pressure-compensated intake valve is built and the experiment is carried out, simulation and experimental results of the CAE are conducted, and pressures inside the cylinder and output torque of the CAE are obtained. Orthogonal design and grey relation analysis are utilized to optimize structural parameters. The experimental and optimized results show that, first of all, pressure inside the cylinder has the same changing tendency in both simulation curve and experimental curve. Secondly, the highest average output torque is obtained at the highest intake pressure and the lowest rotate speed. Thirdly, the optimization of the single-cylinder CAE can improve the working efficiency from an original 21.95% to 50.1%, an overall increase of 28.15%, and the average output torque increases also increases from 22.047 5 N • m to 22.439 N • m. This research designs a single-cylinder CAE with pressure-compensated intake valve, and proposes a structural parameters design method which improves the single-cylinder CAE performance.
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Papers by Qihui Yu